Viagra, containing sildenafil, is a medication used to treat erectile dysfunction (ED) in men. Its main benefit is improving blood flow to the penis, aiding in achieving and sustaining an erection. This drug typically comes in 25mg, 50mg, and 100mg doses, with 100mg being a standard dose for many users. Viagra works by relaxing muscles in blood vessel walls, allowing increased blood flow to specific areas of the body, crucial for an erection. It's important to note that Viagra doesn't cause spontaneous erections; sexual arousal is necessary for it to be effective.